EP0239816B1 - N,N'-substituted bis-(2,4-diamino-s-triazin-6-yl)-tetrasulphides and their disproportionation products, process for their preparation and their use in vulcanisable rubber mixtures - Google Patents

Abstract

Compounds of the general formula <IMAGE> in which R<1>, R<2> denote H; R<2> denotes benzyl, R<2>, R<3>, R<4> denote C1-C8-alkyl, allyl, C3-C8-cycloalkyl, the latter being unsubstituted or substituted by 1-3 methyl groups, 2-hydroxyethyl, 3-hydroxypropyl, 2-hydroxypropyl or R<3> and R<4> (together) denote C4-C6-alkylene, -(CH2-CHX)2Y where X is H, CH3 and Y is O, S and their oligosulphide disproportionation products, whose average statistical chain length corresponds to S4 are prepared from the corresponding N,N'-substituted diaminomercaptotriazines. The substances according to the invention are used in vulcanisable rubber mixtures as crosslinking agents without sulphur or as vulcanisation accelerators together with sulphur.

Description

The invention relates to N, N'-substituted bis (2,4-diamino-s-triazin-6-yl) tetrasulfides, a process for their preparation, processes for the preparation of their disproportionation products, the use of the tetrasulfides and the disproportionation products as crosslinking agents or vulcanization accelerators in rubber compounds and vulcanizable rubber compounds containing them.

N, N'-substituted bis (2,4-diamino-s-triazin-6-yl) disulfides are known; they are described in DE-A-1 669 954. They are prepared from the corresponding N, N'-substituted 2,4-diamino-6-mercaptotriazines by oxidation, for example with iodine, sodium hypochlorite or hydrogen peroxide. The best known compound in this group is bis (2-ethylamino-4-di-ethylamino-triazin-6-yl) disulfide. Disulfides from this group can be used as accelerators in rubber compounds.

The aim of the invention is to develop compounds which improve the vulcanization behavior of rubber compounds and give their vulcanizates better properties, and methods for producing these compounds.

The subject of the invention are Compounds of the general formula

in welcher bedeuten:

• R^l, R² = H, R² = Benzyl
• R², R³, R⁴ = C₁-C₈-Alkyl, bevorzugt C1-C4-Alkyl, verzweigt oder unverzweigt, Allyl, C₃-C₈-Cycloalkyl, letzteres unsubstituiert oder mit 1-3 Methylgruppen substituiert, 2-Hydroxyethyl, 3-Hydroxypropyl, 2-Hydroxypropyl,
  mit Ausnahme des in der EP-A-0 178 444 vorbeschriebenen aber nicht vorveröffentlichten Bis-(2-Ethylami- no-4-diethylamino-s-triazin-6-yl)tetrasulfids Gegenstand der Erfindung ist ebenso ein Verfahren zur Herstellung dieser Verbindungen. Das Verfahren zur Herstellung der reinen Tetrasulfide mit einer linearen S₄-Kette zwischen den beiden substituierten Triazinresten ist dadurch gekennzeichnet, daß man eine wässrige, alkalische Lösung der entsprechenden N,N'-substituierten 2,4-Diamino-6-mercaptotriazinein einem Zweiphasensystem mit einer S₂C1₂-Lösung in einem inerten organischen Lösungsmittel, in welchem das Reaktionsprodukt nicht oder sehr wenig löslich ist, bei Temperaturen zwischen -5 ° C -< + 20 _° C, vorzugsweise von + 10 ° C, umsetzt. Vorteilhaft stellt man eine alkalische wässrige Lösung des Mercaptotriazins her, die mindestens die zur Umsetzung notwendige stöchiometrische Menge an Alkalihydroxid, bevorzugt einen überschuß von 1 - 20 Mol%, bezogen auf das eingesetzte Mercaptotriazin, enthält.

in which mean:

• R ¹ , R ² = H, R ² = benzyl
• R ² , R ³ , R ⁴ = C ₁ -C ₈ alkyl, preferably C1-C4 alkyl, branched or unbranched, allyl, C ₃ -C ₈ cycloalkyl, the latter unsubstituted or substituted with 1-3 methyl groups, 2- Hydroxyethyl, 3-hydroxypropyl, 2-hydroxypropyl,
  with the exception of the bis- (2-ethylamino-4-diethylamino-s-triazin-6-yl) tetrasulfide described but not prepublished in EP-A-0 178 444. The invention also relates to a process for the preparation of these compounds. The process for the preparation of the pure tetrasulfides with a linear S ₄ chain between the two substituted triazine residues is characterized in that an aqueous, alkaline solution of the corresponding N, N'-substituted 2,4-diamino-6-mercaptotriazine is used in a two-phase system an S ₂ C1 ₂ solution in an inert organic solvent, in which the reaction product is insoluble or only slightly soluble, at temperatures between -5 ° C.- <+ 20 _° C., preferably of + 10 ° C. It is advantageous to prepare an alkaline aqueous solution of mercaptotriazine which contains at least the stoichiometric amount of alkali metal hydroxide required for the reaction, preferably an excess of 1-20 mol%, based on the mercaptotriazine used.

This solution is mixed with a solvent in which the end product of the reaction is insoluble or only slightly soluble, preferably with C ₅ -C ₁₀ alkanes, C ₅ -C ₈ cycloalkanes, optionally substituted with 1 to 3 methyl groups and mixtures thereof. This mixture is stirred vigorously and cooled, preferably to + 10 ° C. A solution of S ₂ Cl ₂ in the solvent used is then added dropwise to this mixture with good cooling. S ₂ C1 ₂ is used at least in a ratio of 2 moles of mercaptotriazine: 1 mole of S ₂ C1 ₂ , but this ratio can also be 2: 1.1-1.2, depending on the excess of alkali.

Under the given conditions, S ₂ Cl ₂ acts exclusively as a condensation.

The resulting product is separated off using generally known measures and advantageously dried at temperatures up to +50 ° C. under vacuum 13.3-102 Pa (10 torr).

The application also relates to mixtures consisting of compounds of the general formula

in der R¹, R², R³ und R⁴ dieselben Bedeutungen wie in Anspruch 1 haben und S_x einer mittleren statistischen Kettenlänge mit x = 4 entspricht, mit Ausnahme des Bis-(2-Ethylamino-4-diethylamino-s-triazin-6-yl-)tetrasulfids.

in which R ¹ , R ² , R ³ and R ^{4 have the} same meanings as in claim 1 and S _x corresponds to an average statistical chain length with x = 4, with the exception of bis- (2-ethylamino-4-diethylamino-s-triazine) -6-yl-) tetrasulfide.

These mixtures, also called oligosulfides or disproportionates in the following text, since they are formed by disproportionation of compounds of the formula I, can be prepared in several ways.

The reaction conditions should be controlled so that no free sulfur is formed.

A process is characterized in that the isolated compound according to formula 1 is heated above its melting point, preferably by 20-50 _° C.

In a further process, the compounds of the formula I are dissolved in an inert organic solvent and the disproportionation reaction is carried out in the temperature range between 20 _° C. (standing at room temperature) and the boiling point of the solvent used.

A particularly elegant method is that an aqueous alkaline solution of the corresponding N, N'-substituted 2,4-diamino-6-mercaptotriazines in a two-phase system with a solution of S ₂ CI ₂ in an inert organic tetrasulfide which dissolves Implement solvent. The resulting tetrasulfide is then immediately disproportionated into the mixture according to the invention, consisting of oligosulfides.

Particularly suitable solvents are chlorinated hydrocarbons, for example CH ₂ Cl ₂ and CHCl ₃ , but ethers, esters and aromatic hydrocarbons and ketones are also suitable for the disproportionation reaction. According to claim 9, they can be used if they form a two-phase mixture with water. The reaction conditions for the preparation of the disproportionates are otherwise identical to those for the preparation of compounds of the formula I.

The invention also relates to the use of the claimed compounds in vulcanizable rubber mixtures and to the rubber mixtures themselves containing the compounds according to the invention.

The tetrasulfides or their disproportionates according to the invention, when used as crosslinkers or vulcanization accelerators, are clearly superior to the standard compounds used today.

The rubber processing industry has an extensive range of accelerators (J. van Alphen, Rubber Chemicals (1977, pp. 1-46)) available, preferably for sulfur vulcanization, for example benzothiazolylsulfenamides, benzothiazolyl disulfide and 2-mercaptobenzothiazole or their zinc salts. There are also a number of special compounds, such as thiuram disulfides and peroxides, which act as crosslinkers even without additional sulfur additives, but are often used in combination with sulfur as accelerators. The type of use depends on the effect to be achieved.

In terms of quantity, the greatest importance in practical application, in particular in the case of the elastomers accessible to accelerated sulfur vulcanization, is of today benzthiazolylsulfenamides.

However, new production processes and new articles and the need for constant rationalization have changed the application requirements for accelerators in recent years to an extent that it can already cause difficulties today, the quality requirements placed on the vulcanization process and the properties of the vulcanizates to comply with the accelerators or crosslinkers available today for accelerated sulfur vulcanization.

Another disadvantage of some conventional accelerators (e.g. some sulfenamides, thiurams) that can no longer be neglected today is that amines can be released during the vulcanization process, which - insofar as they are nitrosable - lead to the formation of nitrosamines in the vulcanizate, which - if they are toxic are - can be expected in the long run, a limitation of the possible uses of these accelerators.

A very significant disadvantage of the benzthiazolyl accelerators, in particular the benzthiazolylsulfenamides, is their tendency to reversion, which increases with increasing vulcanization temperature, when the vulcanizates are inevitably often overheated, especially when using types of rubber which are prone to reversion, such as natural rubber and polyisoprene, and their blends with synthetic rubber. The same also applies to synthetic rubbers of all kinds, provided that the reversion process is not covered by thermal crosslinking. Especially with increasing vulcanization temperature, the reversion rate increases so strongly that firstly there is a noticeable reduction in the crosslinking density even with optimal vulcanization, and secondly that the optimum vulcanization takes the form of a peak instead of a plateau, which makes it extremely difficult to reproducibly maintain optimal vulcanizate properties and that thirdly, in the over-vulcanization that is necessary in many cases, an inevitable drop in the crosslinking density occurs, which in particular with thick-walled rubber articles leads to the lifting of the uniformity of the crosslinking in the vulcanizate. As the reversion increases, the performance of the vulcanizates decreases, e.g. in a reduced 300% modulus and abrasion resistance, etc.

To a certain extent, the reduction in sulfur and the increase in the proportion of accelerators, ie the use of so-called semi-EV systems (L. Bateman, 1963 "The Chemistry and Physics of rubber-like substances", p. 522 ff), leads to one Mitigation of the described reversion effects. This mitigation of the reversion is achieved by changing the crosslinking structure (ratio of -S _x- , -SS-, -S bonds) in favor of monosulfidic crosslinking sites, which can adversely affect the vulcanizate properties. However, the higher the vulcanization temperature, the more ineffective this measure becomes.

These disadvantages of the benzothiazole accelerators limit their usability with increasing vulcanization temperature and set certain limits to the efforts of the rubber industry to increase productivity by using higher vulcanization temperatures.

Surprisingly, the N, N'-substituted bis- (2,4-diamino-s-triazin-6-yl) tetrasulfides according to the invention and their disproportionation products have been found both with regard to their use as accelerators in sulfur vulcanization and their use as crosslinkers, ie without the additional use of sulfur, as compounds which give the rubber mixtures produced therewith extremely high reversion stability even at high vulcanization temperatures - even in the case of very strong overheating - in that the reversion process which is otherwise customary when they are used either does not occur at all or if, then only in to a small extent. The surprising fact that the crosslinking sites formed by the N, N'-substituted bis- (2,4-diamino-s-triazin-6-yl) tetrasulfides or their disproportionates proved to be extraordinarily stable to reversion and thermostability, When used in rubber mixtures, even at high vulcanization temperatures, this leads to a high level of performance of the vulcanizates being achieved on the one hand after completion of the crosslinking reaction and, on the other hand, to the fact that the high level of performance is maintained for a long time even when strongly overheated.

Taken together, these two effects enable increases in productivity in the rubber processing industry by increasing the vulcanization temperature without loss of vulcanizate performance.

Even approximately the same resistance to reversion cannot be achieved with commercially available polysulfides such as Robac @ P 25 (Robinson, dipentamethylene thiuram tetrasulfide) and Tetron @ A (Du Pont, dipentamethylene thiuram hexasulfide) or with dibenzthiazolyl tetrasulfide.

The use of the N, N'-substituted bis (2,4-diamino-s-triazin-6-yl) tetrasulfides claimed according to the invention and their disproportionation products includes the rubber mixtures known from the prior art based on natural rubber (NR) , Isoprene rubber (IR), butadiene rubber (BR) styrene-butadiene rubber (SBR), isobutylene-isoprene rubber (IIR), ethylene-propylene terpolymer (EPDM), nitrile rubber (NBR), halogen-containing rubbers and also epoxidized natural rubbers (ENR) and their compounds . The use of the N, N'-substituted bis- (2,4-diamino-s-triazin-6-yl) tetrasulfides and their disproportionation products in the case of the types of rubbers susceptible to reversion, such as natural rubber, isoprene and butadiene, is of particular importance -Rubbers, as well as their blends with each other or with other rubbers.

The N, N'-substituted bis- (2,4-diamino-s-triazin-6-yl) tetrasulfides and their disproportionation products claimed according to the invention are used as crosslinking agents in rubber mixtures in an amount of 0.2 - 15 parts, preferably 0.3 - 8 parts by weight, per 100 parts of rubber.

In accelerated sulfur vulcanization, the N, N'-substituted bis- (2,4-diamino-s-triazin-6-yl) tetrasulfides or their disproportionation products as accelerators are used as accelerators in amounts of 0.01-10 parts, preferably 0.1 5 parts based on 100 parts of rubber, one at sulfur doses of 0.1-10 parts. A molar ratio of the accelerators according to the invention to sulfur (S ₈ ) of 1: 0.5-1.5 is preferred. To achieve a certain range of variation in the vulcanization kinetics, it may prove expedient to use 2 or more N, N'-substituted bis (2,4-diamino-s-triazin-6-yl) tetrasulfides or their disproportionates in a mixture, in order to maintain the abovementioned application amounts, in particular the preferred accelerator / sulfur ratio, the substitution is to be carried out on a molar basis. The same applies when using the N, N'-substituted bis- (2,4-diamino-s-triazin-6-yl) tetrasulfides or their disproportionates as crosslinkers without sulfur.

Also for kinetic reasons, it may prove expedient to use the N, N'-substituted bis- (2,4-diamino-s-triazin-6-yl) tetrasulfides or their disproportionation products in a mixture with conventional accelerators such as e.g. Sulfenamids and thiurams to use. These measures are sometimes detrimental to the resistance to reversion compared to the N, N'-substituted bis- (2,4-diamino-s-triazin-6-yl) tetrasulfide vulcanizates, but they have an inversely positive effect on the reversion behavior, if conventional accelerators are partially replaced by N, N'-substituted bis (2,4-diamino-s-triazin-6-yl) tetrasulfides or their disproportionates.

A further significant influence on the incubation time when using the compounds according to the invention in rubber mixtures can be achieved by combining them with commercially available vulcanization retarders, such as Santoguard @ PVI (N- (cyclohexylthio) phthalimide), Vulkalent @ E (N-phenyl-N- (trichloromethylsulphenyl) - benzenesulfonamide) can be achieved. The Vulkalent @ E from Bayer AG has proven to be the most effective retarder. With increasing Vulkalent @ E addition, there is a linear increase in the incubation time of N, N'-substituted bis- (2,4-diamino-s-triazin-6-yl) tetrasulfides or mixtures containing their disproportionates.

When using N, N'-substituted bis- (2,4-diamino-s-triazin-6-yl) tetrasulfides or their disproportionation products as crosslinkers, it has been observed that the molar ratio of N, N'-substituted bis- ( 2,4-diamino-s-triazin-6-yl) tetrasulfides or their disproportionates to Vulkalent E of 1: 0.5-1.5 preferably 0.8-1.2 parts per 100 parts of rubber have been found to be expedient.

The use of retarders, in particular Vulkalent E, in accelerated sulfur vulcanization using N, N'-substituted bis- (2,4-diamino-s-triazin-6-yl) tetrasulfides and their disproportionates and mixtures is of greater importance the same. In addition to the intended increase in the incubation time of the crosslinking reaction, one occasionally observes a slight impairment of the crosslinking rate, which can, however, be compensated for by an increase in temperature and a slight decrease in the resistance to reversion. In this case it has also been found to be expedient to reduce the molar ratio of N, N'-substituted bis- (2,4-diamino-s-triazin-6-yl) tetrasulfides or their disproportionates to Vulkalent E to 1: 0.5-1.5, preferably 1: 0.8-1.2, the sulfur content depending on the type of mixture being between 0.1-10 parts, preferably 0.5-8 parts, based on 100 parts of rubber.

With these dosage guidelines, many of the vulcanization problems posed can be solved without a significant loss of vulcanizate properties contrary to the essence of the invention. Mixtures that contain only silica or soot / silica blends with higher proportions of silica than 15 parts / 100 parts of rubber are difficult, if at all, to crosslink with conventional sulfur vulcanization systems. On the one hand, they are particularly subject to reversion, on the other hand, they prevent the setting of the crosslink density, which is specified by the requirements for finished articles. This is one of the reasons why silicas are preferably used in sole material and, until today, relatively rarely in dynamically stressed articles.

Surprisingly, bis- (2,4-diamino-s-triazin-6-yl) tetrasulfides and their disproportionates succeed in mixtures which contain black and white blends with silica components of more than 15 parts / 100 parts of rubber and also with mixtures filled with silica, practically eliminating reversion both when used as an accelerator and as a crosslinker (without sulfur) and at the same time increasing the crosslinking density, which is expressed in a high voltage level for silica mixtures.

mit

• x = 2 - 6, R = C1-C6-Alkyl, Cyclohexyl
• n = ₂ oder 3
  beziehungsweise
  
  mit
• x = 2 - 6, bevorzugt 3,
  vorzugsweise Bis-(3-triäthoxisilylpropyl)-Tetrasulfid (Si 69, Degussa AG). N,N'-substituierte Bis-(2,4-diamino- s-triazin-6-yl)-Tetrasulfide und deren Disproportionate lassen sich sowohl bei der schwefelfreien Organosilan-Vernetzung anstelle der in DE-A-25 36 674 beschriebenen Beschleuniger vorteilhaft verwenden als auch bei der in DE-A-22 55 577 beschriebenen Schwefelvulkanisation mit Organosilanen und ebenso bei Herstellung reversionsstabiler Organosilan-haltiger Kautschukmischungen durch Aufbau von equilibrium cure systems gemäß DE-A-28 48 559.

Another application of the N, N'-substituted bis- (2,4-diamino-s-triazin-6-yl) tetrasulfides and their disproportionation products is in combined use with oligosulfidic organosilanes, for example

With

• x = 2-6, R = C1-C6 alkyl, cyclohexyl
• n = ₂ or 3
  respectively
  
  With
• x = 2-6, preferably 3,
  preferably bis (3-triethoxysilylpropyl) tetrasulfide (Si 69, Degussa AG). N, N'-substituted bis- (2,4-diamino-s-triazin-6-yl) tetrasulfides and their disproportionates can be used both in the sulfur-free organosilane crosslinking instead of the accelerators described in DE-A-25 36 674 use as well in the sulfur vulcanization with organosilanes described in DE-A-22 55 577 and also in the production of reversion-stable organosilane-containing rubber mixtures by building up equilibrium cure systems according to DE-A-28 48 559.

This applies both to soot-filled mixtures and to mixtures which contain soot / silica blends, as well as to mixtures which are built up using only silica. The addition of mineral fillers does not have any adverse effects in any of the mixtures mentioned. Rubber / filler bonds are formed in the presence of silica fillers or blends of soot with silicas (rubber + rubber, plastics, issue 8, 1977, pp. 516-523, issue 10, 1979, pp. 760-765 and issue 4 , 1981), pp. 280-284) or in the presence of carbon black rubber / rubber bonds.

The formation of rubber / rubber crosslinking sites in the presence of carbon black or that of rubber / filler crosslinking sites in the presence of silica and of both types of bonds in the case of carbon black / silica blends of all ratios also succeeds if N, N'-substituted bis- ( 2,4-diamino-s-triazin-6-yl) tetrasulfides or their disproportionates can be used alone or in a mixture of several or in a mixture with conventional accelerators together with conventional sulfur donors such as, for example, sulfasan ( ^R ) R (morpholine disulfide).

• - übliche Verstärkungssysteme, d.h. Furnace-Ruß, Channel-Ruße, Flammruße, Thermalruße, Acetylenru- ße, Lichtbogenruße, CK-Ruße usw. sowie synthetische Füllstoffe wie Kieselsäuren, Silikate, Aluminiumoxidhydrate, Calciumcarbonate und natürliche Füllstoffe wie Clays, Kieselkreiden, Kreiden, Talke usw. sowie silanmodifizierte Füllstoffe und deren Verschnitte in Mengen von 5 - 300 Tln. je 100 Tle. Kautschuk, bevorzugt sind insbesondere Kieselsäuren und Silikate,
• - ZnO und Stearinsäure als Promotoren der Vulkanisation in Mengen von 0.5 - 10 Tln. Kautschuk,
• - üblicherweise verwendete Alterungs-, Ozon-, Ermüdungsschutzmittel wie zum Beispiel IPPD, TMQ sowie auch Wachse als Lichtschutzmittel und deren Verschnitte.
• - beliebige Weichmacher wie zum Beispiel aromatische, naphthenische, paraffinische, synthetische Weichmacher und deren Verschnitte,
• - ggfs. weitere Silane wie -Chlorpropyltrialkoxisilane, Vinaltrialkoxysulane, und Aminoalkyltrialkoxisilane, sowie deren Verschnitte in einer Menge von 0.1 - 15, bevorzugt 1 - 10 Tle. je 100 Tle. silanolgruppentragender Füllstoffe wie Kieselsäuren, Silikate, Clays usw.
• - ggfs. Farbstoffe und Verarbeitungshilfsmittel in der üblichen Dosierung.

The compound according to the invention as claimed in claims 1 to 11 is used in rubber mixtures which may contain further customary components, for example:

• - Common reinforcement systems, ie furnace black, channel black, flame black, thermal black, acetylene black, electric black, CK black, etc., as well as synthetic fillers such as silicas, silicates, aluminum oxide hydrates, calcium carbonates and natural fillers such as clays, pebbles, chalks, talk etc. as well as silane-modified fillers and their blends in amounts of 5 to 300 parts per 100 parts of rubber, in particular silicas and silicates are preferred,
• ZnO and stearic acid as promoters of vulcanization in quantities of 0.5-10 parts rubber.
• - Usually used anti-aging, anti-ozone, anti-fatigue agents such as IPPD, TMQ as well as waxes as light stabilizers and their blends.
• any plasticizers such as aromatic, naphthenic, paraffinic, synthetic plasticizers and their blends,
• - If necessary, further silanes such as chloropropyltrialkoxysilanes, vinaltrialkoxysulanes, and aminoalkyltrialkoxysilanes, and their blends in an amount of 0.1-15, preferably 1-10, parts per 100 parts of fillers containing silanol groups, such as silicas, silicates, clays, etc.
• - If necessary, dyes and processing aids in the usual dosage.

The field of application of the N, N'-substituted bis- (2,4-diamino-s-triazin-6-yl) tetrasulfides extends to rubber mixtures according to claims 13 to 16 as are customarily used in tire construction and to technical articles, such as mixtures for conveyor belts, V-belts, molded articles, hoses with and without inlays, roller rubbers, linings, injection profiles, free hand items, foils, shoe soles and uppers, cables, solid rubber tires and their vulcanizates.

• A Bis-(2-ethylamino-4-di-isopropylamino-s-triazin-6-yl)-tetrasulfid
• B Bis-(2-n-butylamino-4-diethylamino-s-triazin-6-yl)-tetrasulfid
• C Bis-(2-isopropylamino-4-di-isopropylamino-s-triazin-6-yl)-tetrasulfid
• D Bis-(2-ethylamino-4-di-isobutylamino-s-triazin-6-yl)-tetrasulfid
• E Bis-(2-ethylamino-4-di-n-propylamino-s-triazin-6-yl)-tetrasulfid
• F Bis-(2-n-propylamino-4-diethylamino-s-triazin-6-yl)-tetrasulfid
• G Bis-(2-n-propylamino-4-di-n-propylamino-s-triazin-6-yl-)-tetrasulfid
• H Bis-(2-n-butylamino-4-di-n-propylamino-s-triazin-6-yl)-tetrasulfid
• I Bis-(2-ethylamino-4-di-n-butylamino-s-triazin-6-yl)-tetrasulfid
• K Bis-(2-isopropylamino-4-di-isopropylamino-s-triazin-6-yl)-oligosulfidgemisch
• L Bis-(2-cyclohexylamino-4-diethylamino-s-triazin-6-yl)-oligosulfidgemisch
• M Bis-(2-ethylamino-4-diethylamino-s-triazin-6-yl)-oligosulfidgemisch
• O Bis-(2-amino-4-diethylamino-s-triazin-6-yl)-oligosulfidgemisch

The following products are mentioned as examples of compounds according to the invention:

• A bis (2-ethylamino-4-di-isopropylamino-s-triazin-6-yl) tetrasulfide
• B bis (2-n-butylamino-4-diethylamino-s-triazin-6-yl) tetrasulfide
• C bis (2-isopropylamino-4-di-isopropylamino-s-triazin-6-yl) tetrasulfide
• D bis (2-ethylamino-4-di-isobutylamino-s-triazin-6-yl) tetrasulfide
• E bis (2-ethylamino-4-di-n-propylamino-s-triazin-6-yl) tetrasulfide
• F bis (2-n-propylamino-4-diethylamino-s-triazin-6-yl) tetrasulfide
• G bis (2-n-propylamino-4-di-n-propylamino-s-triazin-6-yl -) tetrasulfide
• H bis (2-n-butylamino-4-di-n-propylamino-s-triazin-6-yl) tetrasulfide
• I bis (2-ethylamino-4-di-n-butylamino-s-triazin-6-yl) tetrasulfide
• K bis (2-isopropylamino-4-di-isopropylamino-s-triazin-6-yl) oligosulfide mixture
• L bis (2-cyclohexylamino-4-diethylamino-s-triazin-6-yl) oligosulfide mixture
• M bis (2-ethylamino-4-diethylamino-s-triazin-6-yl) oligosulfide mixture
• O bis (2-amino-4-diethylamino-s-triazin-6-yl) oligosulfide mixture

Reference - Example 1:

This is Example 1 described in EP-A-0 178 444.

454 g of 2-ethylamino-4-diethylamino-6-mercaptotriazine are dissolved in sodium hydroxide solution, which has been prepared from 84 g of NaOH + 1.5 liters of H ₂ O.

The solution is poured into a 4 liter 3 tube flask, then 1.5 liters of light petrol (bp 80-110 ° C) are added and the mixture is cooled to 0 ° C with vigorous stirring.

Now you can leave within 20 min. run a solution of 137 g S ₂ C1 _{2 in} 100 ml of gasoline, taking care that the temperature does not exceed +5 ° C.

The tetrasulfide precipitates immediately. At the end of the reaction, 5 min. stirred, then suction filtered and washed.

The snow-white fine powder is dried in a vacuum of 15.96-102 Pa (12 torr) at 40 - 45 ° C. Quantity: 499.5 g, corresponding to 97.1% of theory, mp 149-150 ° C.

• Bis-(2-ethylamino-4-diethylamino-s-triazin-6-yl)-Tetrasulfid,
• Molgew. 516, C₁₈H₃₂N₁₀S₄
  

Analysis:

• Bis- (2-ethylamino-4-diethylamino-s-triazin-6-yl) tetrasulfide,
• Molgew. 516, C ₁₈ H ₃₂ N ₁₀ S ₄
  

TLC and HPLC analysis show that the product contains 97.1% linear tetrasulfide.

Example 2:

56.6 g of 2-ethylamino-4-di-n-butylamino-6-mercaptotriazine are dissolved in a solution of 8.8 NaOH in 250 ml of water. Add 250 ml of gasoline. After stirring well, the mixture is cooled to +5 ° C. A solution of 13.5 g of S ₂ C1 ₂ in 30 ml of gasoline is then run in. A white precipitate forms immediately. At the end of the reaction the mixture is worked up according to Example 1. Quantity: 56 g, corresponding to 89.2% of theory.

HPLC analysis: purity> 96%.

Example 3:

107.6 g of 2-i-propylamino-4-diisopropylamino-6-mercaptotriazine are dissolved in sodium hydroxide solution, which is prepared from 17.6 g of NaOH in 600 ml of H ₂ O. 600 ml of methylene chloride are added.

A solution of 27 g of S ₂ CI ₂ in 50 ml of CH ₂ CI _{2 is} run in at 0-5 ° C. At the end of the reaction, the organic phase is separated off in a separating funnel, dried and evaporated in vacuo. An amorphous powder is obtained; Softening point: 90 ° C. Yield: 112.5 g, corresponding to 94% of theory.

Example 4:

45.4 g of 2-ethylamino-4-diethylamino-6-mercaptotriazine are dissolved in sodium hydroxide solution, prepared from 8.8 g of NaOH and 200 ml of water. 200 ml of methylene chloride are added. The mixture is turbinated and cooled to 0 ° C. 14 g of S ₂ C1 _{2 are} now dissolved in 50 ml of CH ₂ CI ₂ and this solution is run into the mercaptide solution.

The reaction product dissolves in CH ₂ Cl ₂ . At the end of the reaction, the phases are separated and the CH ₂ C1 ₂ solution is worked up. An amorphous powder is thus obtained with a softening point of approx. 110 ° C. Amount: 46.7 g, corresponding to 90.5% of theory.

According to TLC analysis, a mixture of 4 oligosulfides is contained, but no free sulfur

Example 5:

50 g of bis (2-ethylamino-4-diethylamino-s-triazin-6-yl) tetrasulfide with a purity of 97.1% are placed in a round bottom flask and heated in an oil bath at 160 ° C. for 1 hour. The melt solidifies cold amorphously. According to TLC analysis, the product contains 3 additional oligosulfides in addition to approx. 50% of the starting product.

Example 6:

70.25 g of 2-cyclohexylamino-4-diethylamino-6-mercaptotriazine are dissolved in 11 g of NaOH and 250 ml of water. 250 ml of chloroform are added. A solution of 16.8 g of S ₂ Cl ₂ in 30 ml of CHCl _{3 is} run in with vigorous stirring. At the end of the reaction, the phase is separated and the chloroform layer is worked up. 71.9 g of a white amorphous powder are obtained, corresponding to 92% of theory.

According to TLC analysis, the product consists of approx. 30% linear S ₄ product and 70% oligosulfides, but does not contain any free sulfur.

Test standards

The physical tests were carried out at room temperature in accordance with the following standards:

Example 7: Reversion stability of N, N'-substituted bis (2,4-diamino-s-triazin-6-yl) tetrasulfide-crosslinked, N 220-filled NR (without sulfur)

Fortsetzung

continuation

Example 7: Reversion stability of N, N-filled NR (without sulfur) crosslinked with N, N'-substituted bis (2,4-diamino-s-triazin-6-yl) oligosulfides

The N, N'-substituted bis (2,4-diamino-s-triazin-6-yl) oligosulfides according to the invention, when used as crosslinking agents (without sulfur), prove to be extremely stable to reversion in soot-filled NR mixtures (mixtures 3-7 ) compared to a semi-EV system (mixture 1) or a mixture containing bis (2-ethylamin-4-diethylamin-s-triazin-6-yl) (V 143) (mixture 2).

Example 8: Reversion stability of N 220 / silica-filled NR (without sulfur) crosslinked with N, N'-substituted bis- (2,4-diamino-s-triazin-6-yl) tetrasulfides

Fortsetzung

continuation

Example 8: Reversion stability of N 220 / silica-filled NR (without sulfur) crosslinked with N, N'-substituted bis (2,4-diamino-s-triazin-6-yl) oligosulfides

Silica-containing NR mixtures show particularly strong reversion phenomena even when using semi-EV systems (mixture 8). With the N, N'-substituted bis- (2,4-diamino-s-triazin-6-yl) tetra- or -oligosulfides (mixture 9-15) used according to the invention as a crosslinker, the mixture composition is otherwise almost the same, and the state is almost reversible reached.

Example 9: Resistance to reversion of N 220-filled NR accelerated with N, N'-substituted bis- (2,4-diamino-s-triazin-6-yl) tetrasulfides

Fortsetzung (1)

Continued (1)

Example 9: Reversion resistance of N, N'-substituted bis- (2,4-diamino-s-triazin-6-yl -) tetrasulfide-accelerated N 220-filled NR

Fortsetzung (2)

Continued (2)

Example 9: Resistance to reversion of N 220 -filled NR accelerated with N, N'-substituted bis (2,4-diamino-s-triazin-6-yl) oligosulfides

With equimolar accelerator dosing, the amount of sulfur can be reduced in the case of the N, N'-substituted bis- (2,4-diamino-s-triazin-6-yl) tetra- or oligosulfides. Nevertheless, higher 300% voltage values are achieved. The mixtures prepared with N, N'-substituted bis- (2,4-diamino-s-triazin-6-yl) tetra- or oligosulfides (mixtures 17-27) have proven to be extremely resistant to reversion against a semi-EV system (Mix 16).

Example 10: Efficacy comparison of sulfenamide-with N, N'-substituted bis- (2,4-diamino-s-triazin-6-yl) tetrasulfide acceleration in N 220-filled NR with the same S ₈ dosage

Example 9 showed the comparison of MOZ against N, N'-substituted bis- (2,4-diamino-s-triazin-6-yl) tetrasulfides or their disproportionation products at different sulfur concentrations. On the other hand, if the sulfur concentration is kept constant with an equimolar amount of accelerator, the reversion difference is retained, but the voltage value increases 300% considerably.

Example 11: Comparison of the reversion behavior of commercially available oligosulfides and dibenzthiazolyl tetrasulfide against N, N'-substituted bis- (2,4-diamino-s-triazin-6-yl) oligosulfide in N 220-filled NR.

Commercial oligosulfides (mix 30 and 31) as well as dibenzthiazolyltetrasulfide (mix 32) show in NR multiple times higher reversion than an N, N'-substituted bis (2,4-diamino-s-triazin-6-yl) oligosulfide ( Mix 33).

Example 12: Blending of N.N'-substituted bis-2,4-diamino-s-triazin-6-yl -) - tetrasulfide with sulfur donor in N 220-filled NR

Against conventional sulfenamide acceleration (mixture 34) there is a clear improvement in reversion when using N, N'-substituted bis- (2,4-diamino-s-triazin-6-yl) tetrasulfide with sulfasan R as the sulfur donor (mixture 35).

Example 13: Blending of commercial accelerators with N, N'-substituted bis (2,4-diamino-s-triazin-6-yl) tetrasulfide in N 220-filled NR

Fortsetzung

continuation

Example 13: Blending of commercial accelerators with N, N'-substituted bis- (2,4-diamino-s-triazin-6-yl -) tetrasulfide in N 220-filled NR

The common use of commercial accelerators with N, N'-substituted bis (2,4-diamino-s-triazin-6-yl) tetrasulfides (mixtures 37, 40, 41) leads to a clear improvement in the reversion behavior compared to sole use of the commercial accelerators (mixtures 36, 39, 42). A further increase in the resistance to reversion can be achieved by eliminating the sulfur (mixtures 38, 41, 44).

Example 14: Blending of N, N'-substituted bis (2,4-diamino-s-triazin-6-yl -) tetrasulfide with N, N'-substituted bis- (2,4-diamino-s-triazine -6-yl) oligosulfide in N 220 filled NR.

The combined use of N, N'-substituted bis- (2,4-diamino-s-triazin-6-yl) tetrasulfides with different reversion resistance results in an image that lies between the pure substances (mixture 48).

Example 15: Reversion on acceleration with B in NR with soot / silica blends.

When the sulfenamide accelerator (mixture 49) is replaced by N, N'-substituted bis (2,4-diamino-s-triazin-6-yl) tetrasulfide (mixture 50), the reversion falls back drastically.

Example 16: N, N'-substituted bis (2,4-diamino-s-triazin-6-yl) tetra and oligosulfides in N 220-filled SBR

With the same sulfur dosage, N, N'-substituted bis- (2,4-diamino-s-triazin-6-yl -) - tetra- or oligosulfides (mixture 52-55) in SBR 1500 show a significantly higher voltage value and slightly improved Reversion properties against conventional acceleration (mixture 51).

Example 17: N, N'-substituted bis- (2,4-diamino-s-triazin-6-yl -) - tetra- or oligosulfides in N 220-filled isoprene rubber

The use of N, N'-substituted bis- (2,4-diamino-s-triazin-6-yl-) tetra- or oligosulfides (mixtures 57-59) against conventional accelerators (mixture 56) is also used in polyisoprene rubber achieved a significant improvement in reversion. This improvement can also be seen in the consistency of the vulcanizate data with significant overheating.

Example 18: N, N'-substituted bis (2,4-diamino-triazin-6-yl) tetra- and oligosulfides in N 220-filled EPDM

Already highly-resistant EPDM mixtures show a further reduction of the reversion to zero when conventional accelerator mixtures (mixture 60) with N, N'-substituted bis- (2,4-diamino-s-triazin-6-yl) tetra- or oligosulfides to be replaced (mixtures 61 and 62).

Example 19: N, N'-substituted bis- (2,4-diamino-s-triazin-6-yl -) tetra and oligosulfides in N 220 filled NBR

With the same sulfur content, the reference mixture (mixture 63) is substituted by N, N'- substituted bis- (2,4-diamino-s-triazin-6-yl -) - tetra- or oligosulfides (mixtures 64 and 65) in NBR a strong increase in the stress value at 300% elongation with a simultaneous reduction in reversion.

Example 20: Reversion stability of N, N'-substituted bis (2,4-diamino-s-triazin-6-yl) oligo sulfides in N 220-filled BR

Due to the lower reversion of the M and D accelerated BR mixtures (mixtures 67 and 68), the drop in voltage value 300% in the case of severe overheating is significantly reduced compared to the reference mixture (mixture 66).

Example 21: N, N'-substituted bis- (2,4-diamino-s-triazin-6-yl -) - tetra and oligosulfides in N 220-filled NR / BR blend

Mixtures 70 to 72 show a significant reduction in reversion when using N, N'- substituted bis- (2,4-diamino-s-triazin-6-yl -) - tetra- and oligosulfides against a semi-EV- System (mix 69) in a blend of NR and polybutadiene.

Example 22: Crosslinking of 50% epoxidized natural rubber (ENR 50) with N 220 filling with N, N'-substituted bis- (2,4-diamino-s-triazin-6-yl) tetra- or oligosulfide

At the same tension value at 300% elongation and considerably increased tensile strength, the replacement of a conventional acceleration (mixture 73) with N, N'-substituted bis- (2,4-diamino-s-triazin-6-yl -) - tetra- respectively -oligosulfides (mixtures 74 and 75) for an additional improvement in reversion.

Example 23: Effect of Vulkalent E on sulfur-free NR crosslinking of N 220- and N 220 / silica-filled NR with N, N'-substituted bis- (2,4-diamino-s-triazin-6-yl -) - tetrasulfides

In N 220 and N 220 / silica filled and cross-linked with C, the Vulkalent E addition achieves the desired extension of the incubation time without impairing the reversion.

Example 24: Retarding effect of Vulkalent E on N, N'-substituted bis- (2,4-diamino-triazin-6-yl) tetra- and oligosulfide vulcanized N 220 / NR mixtures

The addition of Vulkalent E in B and M accelerated mixtures (mixtures 84 and 86) leads to an increase in the incubation time ti above the level of the mixture accelerated conventionally with MOZ (mixture 82).

Example 25: N, N'-substituted bis- (2,4-diamino-s-triazin-6-yl -) - tetrasulfides with Vulkalent-E addition in N 220-filled NR depending on the temperature

Example 25 shows with pure N, N'-substituted bis (2,4-diamino-s-triazin-6-yl) tetrasulfide acceleration (mixture 88) as well as with the addition of Vulkalent E (mixture 89) compared to conventional acceleration (Mixture 87) a pronounced insensitivity to temperature of the reversion.

Example 26: Effect of Vulkalent E on N, N'-substituted bis (2,4-diamino-s-triazin-6-yl) tetrasulfide and oligosulfide cross-linked NR with N 220 / silica

Vulkalent E can be used to accelerate with N, N'-substituted bis- (2,4-diamino-s-triazin-6-yl) tetra- or oligosulfides (mixtures 92 and 94) to achieve a scorch behavior comparable to MOZ.

Example 27: Simultaneous use of N, N'-substituted bis- (2,4-diamino-s-triazin-6-yl -) - tetrasulfide and Si 69 with or without Vulkalent E in N 220 / VN 3-filled NR

When N, N'-substituted bis- (2,4-diamino-s-triazin-6-yl -) - tetrasulfides and Si 69 are used together, reversion-free mixtures with and without sulfur (mixtures 96, 98) are obtained against conventional accelerators with silane (mixture 95). The addition of Vulkalent E also leads to an extension of the scorch time in this case without the reversion occurring again (mixtures 97 and 99).

Example 28: Crosslinking of N 220 / silica-filled NR with N, N'-substituted bis- (2,4-diamino-triazin-6-yl) tetrasulfide without sulfur

The sulfur-free crosslinking with N, N'-substituted bis- (2,4-diamino-triazin-6-yl) tetrasulfide in natural rubber with carbon black and silica filling prevents reversion and at the same time leads to a quantity-dependent voltage increase.

Example 29: Crosslinking of silica-filled NR with N, N'-substituted bis (2,4-diamino-triazin-6-yl) tetrasulfide

The sulfur-free crosslinking with N, N'-substituted bis- (2,4-diamino-triazin-6-yl) tetrasulfide leads to a substantial reduction in reversion in natural rubber with silica filling and at the same time to an increase in the stress value at 300%.

Example 30: Acceleration of N 220 / silica-filled NR with N, N'-substituted bis- (2,4-diamino-triazin-6-yl) tetrasulfide

The sulfur vulcanization with N, N'-substituted bis- (2,4-diamino-triazin-6-yl) tetrasulfide of N 220 / silica-filled NR reduces the reversion to 0% and leads to a strong increase in the stress value.

Example 31: Acceleration of silica-filled NR with N, N'-substituted bis (2,4-diamino-triazin-6-yl) tetrasulfide

The sulfur vulcanization with N, N'-substituted bis- (2,4-diamino-triazin-6-yl) tetrasulfide of silica-filled NR works almost without reversion and increases the 300% tension value.

Example 32: Acceleration of N 220 / silica-filled NR with N, N'-substituted bis- (2,4-diamino-triazin-6-yl) tetrasulfide in the presence of Si 69

Acceleration with N, N'-substituted bis- (2,4-diamino-triazin-6-yl) tetrasulfide in the presence of Si 69 allows the reversion to be reduced to 0% while at the same time significantly increasing the voltage values.

Example 33: Acceleration of silica-filled NR with N, N'-substituted bis- (2,4-diamino-triazin-6-yl) tetrasulfide in the presence of Si 69

Even in the case of pure silicic acid filling, NR is vulcanized in the presence of Si 69 with N, N'-substituted bis- (2,4-diamino-triazin-6-yl) tetradulfide and sulfur without reverse, with the tension value level being raised very sharply at the same time.

Example 34: The sulfur-free crosslinking of N 220 / silica-filled NR with N, N'-substituted bis- (2,4-diamino-triazin-6-yl) tetrasulfide in the presence of Si 69

The sulfur-free crosslinking with N, N'-substituted bis- (2,4-diamino-triazin-6-yl) tetrasulfide leads to a simultaneous prevention of reversion and a strong one in natural rubber with carbon black and silica filling even when Si 69 is added quantity-dependent voltage increase.

Example 35: The sulfur-free crosslinking of silica-filled NR with N, N'-substituted bis- (2,4-diamino-triazin-6-yl) tetrasulfide in the presence of Si 69

The crosslinking with N, N'-substituted bis- (2,4-diamino-triazin-6-yl) tetrasulfide of natural rubber with pure silica filling in the presence of Si 69 also succeeds without a reversal and at the same time leads to a substantial increase in the voltage value.

Claims (18)

1. Compounds corresponding to the following general formula:

in which

R¹, R² = H, R² = benzyl,

R², R³, R⁴ = C_1-8 alkyl, allyl, C₃-₈ cycloalkyl unsubstituted or substituted by 1 to 3 methyl groups, 2-hydroxyethyl, 3-hydroxypropyl, 2-hydroxypropyl,
except for bis-(2-ethylamino-4-diethylamino-3-triazin-6-yl)-tetrasulfide.

2. Mixtures consisting of compounds corresponding to the following general formula:

in which R¹, R², R³ and R⁴ have the same meanings as in claim 1 and S_x corresponds to an average statistical chain length with x = 4,
except for bis-(2-ethylamino-4-diethylamino-s-triazin-6-yl)-tetrasulfide.

3. A process for the production of the tetrasulfides claimed in claim 1, characterized in that an aqueous alkaline solution of the corresponding N,N'-substituted 2,4-diamino-6-mercaptotriazines is reacted in a two-phase system with a solution of S₂CI₂ in an inert organic solvent with little or no dissolving effect on the tetrasulfide formed at temperatures in the range from -5 ° C to < + 20 ° C, the ratio of mercaptotriazine to S₂C1₂ being 2:1 to 2:1.2.

4. A process as claimed in claim 3, characterized in that alkali metal hydroxide is used in at least the stoichiometric quantity required for the reaction.

5. A process as claimed in claims 3 and 4, characterized in that sodium hydroxide or potassium hydroxide is used, C₅-₁₀ alkanes or C_5-8 cycloalkanes, optionally substituted by 1 to 3 methyl groups, being used as the solvent.

6. A process for the production of the mixtures of compounds claimed in claim 2, characterized in that the compounds claimed in claim 1 are disproportionated.

7. A process as claimed in claim 6, characterized in that the tetrasulfides corresponding to formula I are heated beyond their melting point.

8. A process as claimed in claim 6, characterized in that the tetrasulfides corresponding to formula I are dissolved in an inert organic solvent and the disproportionation reaction is carried out at a temperature in the range from 20 _° C to the boiling point of the solvent.

9. A process for the production of the mixtures of compounds claimed in claim 2, characterized in that an aqueous alkaline solution of the corresponding N,N'-substituted 2,4-diamino-6-mercaptotriazines is reacted in a two-phase system with a solution of S₂CI₂ in an inert organic solvent which dissolves the tetrasulfides formed.

10. A process as claimed in claim 9, characterized in that chlorinated hydrocarbons, ethers or esters and aromatic hydrocarbons and ketones insoluble in water are used as the solvent.

11. The use of the compounds according to claims 1 to 10 or mixtures thereof as accelerators in vulcanizable mixtures containing fillers, sulfur and other typical ingredients based on one or more natural and/or synthetic rubber(s) which optionally contain further compounds according to claim 1 or conventional accelerators, more particularly sulfenamides, dibenzthiazolyl disulfide and/or thiurams, sulfur donors and/or retarders and/or organosilanes.

12. The use of the compounds according to claims 1 to 10 or mixtures thereof as crosslinking agents in vulcanizable, sulfur-free mixtures containing fillers and other typical ingredients based on one or more natural and/or synthetic rubber(s) which optionally contain further compounds according to claim 1 or conventional accelerators, more particularly sulfenamides, dibenzthiazolyl disulfide and/or thiurams, sulfur donors and/or retarders and/or organosilanes.

13. Vulcanizable mixtures containing fillers, sulfur and other typical ingredients based on one or more natural and/or synthetic rubber(s), characterized in that they contain 0.01 to 10 parts and preferably 0.1 to 5 parts per 100 parts rubber of the compounds according to claims 1 to 10 and mixtures thereof and/or mixtures with conventional accelerators for sulfur dosages of 0.1 to 10 parts per 100 parts rubber.

14. Vulcanizable mixtures as claimed in claim 13, characterized in that they contain the retarder N-phenyl-N-(trichloromethylsulfenyl)-benzenesulfonamide and the compounds according to claims 1 to 10 or mixtures thereof in a molar ratio of 0.5-1.5:1 and preferably in a molar ratio of 0.8-1.2:1 for a sulfur dosage of 0.1 to 10 parts by weight to 100 parts rubber and preferably 0.5 to 8 parts to 100 parts rubber.

15. Vulcanizable sulfur-free mixtures containing fillers and other typical ingredients based on one or more natural and/or synthetic rubbers, characterized in that they contain 0.2 to 15 parts and preferably 0.3 to 8 parts of the compounds according to claims 1 to 10 or mixtures thereof to 100 parts rubber or mixtures with conventional accelerators.

16. Vulcanizable mixtures as claimed in claim 15, characterized in that they contain the retarder N-phenyl-N-(trichloromethylsulfenyl)-benzenesulfonamide and the compounds according to claims 1 to 10 or mixtures thereof in a molar ratio of 0.5-1.5:1 and preferably 0.8-1.2:1 to 100 parts rubber.

17. Vulcanizable mixtures as claimed in claims 13 to 16, characterized in that they only contain silicas as fillers.

18. Vulcanizable mixtures as claimed in claims 13 to 16, characterized in that, in addition to carbon black, they contain more than 15 parts silica to 100 parts rubber as filler.